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Antihistamine
Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides relief from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects. Antihistamines are usually for short-term treatment. Chronic allergies increase the risk of health problems which antihistamines might not treat, including asthma, sinusitis, and lower respiratory tract infection. Consultation of a medical professional is recommended for those who intend to take antihistamines for longer-term use. Although people typically use the word "antihistamine" to describe drugs for treating allergies, doctors and scientists use the term to describe a class of drug that opposes the activity of histamine receptors in the body. In this sense of the word, antihistamines are subclassified acco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anticholinergic
Anticholinergics (anticholinergic agents) are substances that block the action of the neurotransmitter called acetylcholine (ACh) at synapses in the central and peripheral nervous system. These agents inhibit the parasympathetic nervous system by selectively blocking the binding of ACh to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, sweat glands, and many other parts of the body. In broad terms, anticholinergics are divided into two categories in accordance with their specific targets in the central and peripheral nervous system and at the neuromuscular junction: antimuscarinic agents, and antinicotinic agents (ganglionic blockers, neuromuscular blockers). The term "anticholinergic" is typically used to refer to antimuscarinics which competitively inhibit the binding of ACh to muscarinic acetylcholine receptors; such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aminopyridines
Aminopyridine may refer to any of several chemical compounds: * 2-Aminopyridine * 3-Aminopyridine * 4-Aminopyridine (4-AP), also known as fampridine or dalfampridine {{Short pages monitor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiophenes
Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a planar five-membered ring, it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a benzene-like odor. In most of its reactions, it resembles benzene. Compounds analogous to thiophene include furan (C4H4O), selenophene (C4H4Se) and pyrrole (C4H4NH), which each vary by the heteroatom in the ring. Isolation and occurrence Thiophene was discovered as a contaminant in benzene. It was observed that isatin (an indole) forms a blue dye if it is mixed with sulfuric acid and crude benzene. The formation of the blue indophenin had long been believed to be a reaction of benzene itself. Viktor Meyer was able to isolate thiophene as the actual substance responsible for this reaction. Thiophene and especially its derivatives occur in petroleum, sometimes in concentrations up to 1–3%. The thiophenic content of oil and coal is removed via the hydrodesulfurization (HDS) p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroarenes
In organic chemistry, an aryl halide (also known as haloarene) is an aromatic compound in which one or more hydrogen atoms, directly bonded to an aromatic ring are replaced by a halide. The haloarene are different from haloalkanes because they exhibit many differences in methods of preparation and properties. The most important members are the aryl chlorides, but the class of compounds is so broad that there are many derivatives and applications. Preparation The two main preparatory routes to aryl halides are direct halogenation and via diazonium salts. Direct halogenation In the Friedel-Crafts halogenation, Lewis acids serve as catalysts. Many metal chlorides are used, examples include iron(III) chloride or aluminium chloride. The most important aryl halide, chlorobenzene is produced by this route. Monochlorination of benzene is always accompanied by formation of the dichlorobenzene derivatives. Arenes with electron donating groups react with halogens even in the absence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
